P4S-161 was a planet in the Milky Waygalaxy where Teal'c met with several members of the Jaffa resistance movement. When his meeting ended he attempted to dial Earth, but found he could not achieve a lock. Following protocol, Teal'c dialed the Alpha Site, and soon returned to 161 to ask for a Tel'tak so he could travel to Earth.

Upon his return to 161, Teal'c found the entire rebel movement, hundreds of warriors, dead. Not knowing the planet was now the designated location for resistance leaders, The Trust had struck with a Symbiote poison-enhanced rocket. (SG1: "Endgame")